Research on flexible variable-speed control model and optimization method of rod pumping well based on genetic algorithm

Abstract

The flexible variable-speed control system of rod pumping well is designed to increase the oil production speed and to reduce both the rod stress and motor energy consumption by changing the motor drive speed rapidly during a stroke cycle. This paper establishes a flexible variable-speed control model as well as the optimization algorithm for rod pumping well. The optimal motor speed profile is determined by the optimal Fourier coefficients that maximizes the oil production while satisfies the imposed constrains on stresses in rod and motor torque. Due to the wide range of parameters and the large amount of calculation, the application of genetic algorithms can improve the universal search capabilities, search speed and optimization accuracy. The research and field test show that the variable-speed control model can overcome the inherent defects of the four-link mechanism of the pumping units, improve the performance of the system and reach the maximum production with the lowest energy consumption; Genetic algorithm optimization shows obvious advantages in improving both search speed and optimization accuracy, which provides huge potential in applying flexible variable-speed control of rod pumping well.